Regio- and diastereoselectivity of enol ether formation by 1,4-sigmatropic shifts of hydrogen in carbonyl ylides

Lottes, A. C.; Landgrebe, John A.; Larsen, Kristin

doi:10.1016/s0040-4039(00)99329-8

Cited by 48 publications

(21 citation statements)

References 11 publications

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“…One of the first suggestions that carbonyl ylides derived from metal catalyzed diazo decomposition could proceed via a metal-complexed dipole was made by Landgrebe in 1989 [34]. was found to be catalyst dependent which led Landgrebe to conclude that the catalyst is present during the 1,4-sigmatropic shift of hydrogen [34].…”

Section: Metal-complexed Carbonyl Ylidesmentioning

confidence: 99%

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The interaction of rhodium carbenoids with carbonyl compounds as a method for the synthesis of tetrahydrofurans

Padwa

2005

Journal of Organometallic Chemistry

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Section: Metal-complexed Carbonyl Ylidesmentioning

confidence: 99%

“…was found to be catalyst dependent which led Landgrebe to conclude that the catalyst is present during the 1,4-sigmatropic shift of hydrogen [34].…”

Section: Metal-complexed Carbonyl Ylidesmentioning

confidence: 99%

The interaction of rhodium carbenoids with carbonyl compounds as a method for the synthesis of tetrahydrofurans

Padwa

2005

Journal of Organometallic Chemistry

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“…This reaction type SCHEME 5 SCHEME 4 is well documented [13,14] and is allowed to be concerted by orbital control. It is the counterpart of the 1,5-H shift of 1,3-dienes with adjacent C-H bond.…”

Section: Spiro-134-thiadiazolines Of Fenchane and Camphane Seriesmentioning

confidence: 99%

“…155.8-156.4ЊC (156-157ЊC [32]). 13 . The hydrogenation of 26 with Raney nickel and boiling ethanol was carried out as described previously.…”

Section: -(Methylthio)-␣-fenchene (25)mentioning

confidence: 99%

Thiofenchone s‐methylide and its spiro‐1,3,4‐thiadiazoline precursor

Huisgen

Mlostoń

Pröbstl

2001

Heteroatom Chemistry

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3,4)-thiadiazoline] (6), prepared from thiofenchone and diazomethane, extrudes N 2 (t 1/2 22 min, 46ЊC, toluene) and furnishes the S-methylide 7 which, in turn, closes the thiirane ring or else is intercepted by 1,3-cycloadditions to dipolarophiles (tetracyanoethylene, maleic anhydride, N-methyl-1,2,4-triazoline-3,5-dione, aromatic thioketones). When thiocarbonyl S-methylide 7 is set free in methanol, fenchone S,O-dimethylacetal is formed as an HX adduct. Catalysis by acetic acid converts 7 to 1-(methylthio)-␣-fenchene (25) by way of a Wagner-Meerwein rearrangement. The addition of diazomethane to thiocampher leads, via thiadiazoline 12, to thiocamphor S-methylide; the latter undergoes a 1,4-H shift, thus affording 2-methylthio-2-bornene (11).

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“…It is the counterpart of the sigmatropic 1,5-shift typical for alkylated 1,4-dienes. The chemistry of 1,3-dipoles offers various examples of 1,4-H shifts (e.g., in carbonyl ylides ( oxonium ylides) [23]) and has previously been observed for some thiocarbonyl ylides [24].…”

mentioning

confidence: 99%

Cycloadditions of `Thiocarbonyl Ylides' with Tetracyanoethylene (=Ethenetetracarbonitrile): Interception of Intermediates

Huisgen

Mlostoń

Langhals

2001

HCA

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Dedicated to Edgar Heilbronner on the occasion of his 80th birthday Thiocarbonyl ylides ( sulfonium ylides) belong to the most nucleophilic 1,3-dipoles (high HO energy). In their reactions with tetracyanoethylene (TCNE ethenetetracarbonitrile; low LU energy), a borderline crossing from the concerted mechanism to a two-step pathway via a 1,5-zwitterion was observed. Steric hindrance at one or both termini of the 1,3-dipole is an additional requirement. The ylides 3 and 13, set free by N 2 elimination of dihydro-1,3,4-thiadiazoles, underwent electrocyclization or 1,4-H shift. Ylides 3 and 13 are bases and afforded MeOH adducts of different regiochemistry. Whereas 3 and TCNE in abs. THF at 458 furnished the (3 2) cycloadduct 20, a MeOH content of 0.5 ± 5 vol-% in THF gave rise to a seven-membered lactim ether 22 and thiolane 20 in a 65: 35 ratio (Scheme 4). Water (0.5 ± 1 vol-%) in THF led to lactam 24 and adduct 20 in the same ratio. The zwitterion 26, assumed to be the first intermediate, enters competing reactions: the irreversible ring closure to thiolane 20 and the reversible formation of a strained, cyclic seven-membered ketene imine 28, which is intercepted by MeOH or H 2 O. The gauche-conformation 32 of an analogous zwitterion, produced from the tetrasubstituted thiocarbonyl ylide 13 with TCNE (Scheme 5), led to the thiolane derivative 35, while the anti-conformation 33 afforded the thioxo compound 5 and cyclopropane derivative 36 by intramolecular nucleophilic substitution.

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Regio- and diastereoselectivity of enol ether formation by 1,4-sigmatropic shifts of hydrogen in carbonyl ylides

Cited by 48 publications

References 11 publications

The interaction of rhodium carbenoids with carbonyl compounds as a method for the synthesis of tetrahydrofurans

The interaction of rhodium carbenoids with carbonyl compounds as a method for the synthesis of tetrahydrofurans

Thiofenchone s‐methylide and its spiro‐1,3,4‐thiadiazoline precursor

Cycloadditions of `Thiocarbonyl Ylides' with Tetracyanoethylene (=Ethenetetracarbonitrile): Interception of Intermediates

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